Average chemical structure of mild hydrogenolysis products of coals

Abstract

Three kinds of coal were hydrogenated under mild conditions in a stepwise manner. The total pyridine extraction yields of the products from the three coals were 58.0, 69.9 and 79.5%, respectively. The structural indices of these pyridine extracts show that, as the reaction proceeded, the structure becomes more aromatic and that lower-rank coals have a wider distribution of structural type. The average structural indices were compared with those obtained from the alcohol-alkali reaction products and quinoline extracts. The products of these three reactions gave nearly similar indices, although there was a slight difference. On average, Taiheiyo coal has 1 or 2 aromatic rings with 0.5 naphthenic ring, 3 alkyl chain carbons and 1.5 oxygen atoms in a unit structure. Akabira coal has 2 aromatic rings with 0.4 naphthenic ring, 1.4 aliphatic chain carbons and 1 oxygen atom in a unit structure. Yubari coal has 3 or 4 aromatic rings with 0.5 naphthenic ring, 3 aliphatic chain carbons and 1 oxygen atom in a unit structure.